Makes create_snapshot_bin.py pass along a --package_root flag.

runtime/tools/create_snapshot_bin.py

 #!/usr/bin/env python
 #
 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 """Script to create snapshot bin file."""
 
 import getopt
 import optparse
@@ skipping 12 matching lines @@
   result = optparse.OptionParser()
   result.add_option("--executable",
       action="store", type="string",
       help="path to snapshot generator executable")
   result.add_option("--output_bin",
       action="store", type="string",
       help="output file name into which snapshot in binary form is generated")
   result.add_option("--script",
       action="store", type="string",
       help="Dart script for which snapshot is to be generated")
+  result.add_option("--package_root",
+      action="store", type="string",
+      help="path used to resolve package: imports.")
   result.add_option("--url_mapping",
       default=[],
       action="append",
       help="mapping from url to file name, used when generating snapshots")
   result.add_option("-v", "--verbose",
       help='Verbose output.',
       default=False, action="store_true")
   result.add_option("--target_os",
       action="store", type="string",
       help="Which os to run the executable on. Current choice is android")
@@ skipping 25 matching lines @@
     return 1
 
   # If there are additional arguments, report error and exit.
   if args:
     parser.print_help()
     return 1
 
   # Setup arguments to the snapshot generator binary.
   script_args = ["--error_on_bad_type", "--error_on_bad_override"]
 
+  # Pass along the package_root if there is one.
+  if options.package_root:
+    script_args.append(''.join([ "--package_root=", options.package_root]))
+
   # First setup the snapshot output filename.
   script_args.append(''.join([ "--snapshot=", options.output_bin ]))
 
   # Next setup all url mapping options specified.
   for url_arg in options.url_mapping:
     url_mapping_argument = ''.join(["--url_mapping=", url_arg ])
     script_args.append(url_mapping_argument)
 
   # Finally append the script name if one is specified.
   if options.script:
     script_args.append(options.script)
 
   # Construct command line to execute the snapshot generator binary and invoke.
   command = [ options.executable ] + script_args
   try:
     utils.RunCommand(command, outStream=sys.stderr, errStream=sys.stderr,
                      verbose=options.verbose, printErrorInfo=True)
   except Exception as e:
     return -1
 
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(Main())